Boiler-flue.



` BOILEB FLUE. Arrmoulon runnin. n2, 190s.

` 927 329 Patented July 6, 1909.

Ww d' 13j 20's mmm/gf ANDREW, E. GRmAu co. PnorcAufmomPwzns wAsmNGmn n a /MM www y JOHN M. CROZIER, OF MINNEAPOLIS, MINNESOTA.

BGILER-FLE.

Specification of Letters Patent.

Patented July 6, 1909.

Application filed March 22, 1906. Serial No. 307,503.

To all whom it may concern.'

Be it known that I, JOHN M. Cnozinn, a citizen of the United States, residing at Minneapolis, in the -county of Hennepin and State of Minnesota, have invented certain new and useful Improvements in Boiler Flues and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appcrtains to make and use the same. u

This invention has for its especial object to provide an improved boiler flue, and relates also to an improved process of producing the same.

To the end above noted the invention consists of the boiler iluc having the novel features hereinafter described and defined in the claims.

The boiler flue herein disclosed and claimed was designed to meet the special conditions` presented at the fire box end, in the usage of boiler' flues. It is, of course, well known, that it is much more dil'licult to maintain the flue at the ilire box end, than at the smoke box end, because of the more frequent and sudden changes in the temperature at the fire box end, as in opening the door for firing, which produces sudden expansions and contractions of the flue and flue sheet. Unless the flue, at the iire box end, has walls ol" substantially the same thickness as the flue sheet, the expansion and contraction of the flue and the flue sheet Will be unequal, and, therefore, there will be a tendency to open the joint and produce leakage at that point. Again, unless the flue be thicker at its end than at its body, or main portion, the stock will be further reduced when expanding the flue into its seat and thus the flue Will be weak at that point. Finally, it is desirable to keep the flue seats as small as possible, so as to avoid weakening of the flue sheet by the cutting away of stock to form the seats. This point is of especial importance for replacements or the repairing of old boilers, by the substitution of new flues or flues with new ends. Many of the old flue sheets have their seats or holes so close to each other that they will stand but little, if any, reaming. rllhis replacement or repair problem is of especial importance in respect to traction engines of the kind in general use throughout the northwestern section of the United States, for operating` threshing machines. Most traction engines so employed are straw hurning engines and the feed or supply of this class of fuel is particularly hard on the lire box end of the flue. While it is thus desirable to keep the liue seats as small as possible,

for the reasons above noted, it is also neccslt is immaterial whether it be upset out of the stock of the original tube or whether the `flue he got Vinto form by the addition of an external ring welded thereto in such a way as to (flecreasc the internal diameter of the flue and increase the external (iliarneter thereof. .lt can be accomplished by swaging or by the use of dies, or in any other suitable way. 'The process herein disclosed is, thorefore, only one means by which the said flue can be produced.

In the accompanying drawings which illustrate the invention, like characters indicate like parts tlni'oughout the several views.

Referring to the drawings, Figure l is a view partly in elevation and partly in vertical section showing the imrn'oved boiler flue applied in working position, and Figs. 2, 3 and 4 are fragmentary views illustrating the different forms given to the end of the flue in the process of manufacture.

The numeral l. indicates laterally spaced flue sheets of the boiler to which the flue is shown as applied.

2 indicates one of the ilues. At one end the flue 2 has an inwardly tapered or outwardly flaring upset or thickened annular section 3, the exterior surface of which is conical, and the interior surface of which is of less diameter than the interior of the flue 2. rlhis upset or thickened end section is produced by a novel mode of treatment hereinafter described. The conical exterior of said end section is given a taper of about one-sixteenth of an inch or slightly more, and the inner portion thereof that lioins with. the body of the flue is of but very slight, if any, greater diameter than the exterior surface of the body of the flue.

The walls of flues of different diameter will, of course, have different thicknesses, but for the purpose of this illustration we will assumo that the wall of the flue is one-eighth of an inch in thickness, and that the outer portion of the end section 3 is upset, so that the internal passage through said section at such point is three-thirty seconds less than the internal diameter' of the body of the flue. With these assumed dimensions, we have an upset end section 3 with a maximum thickness of wall of thirteen sixty-fourths of an inch, and with a maximum external diameter only one-sixteenth of an inch greater than the external diameter of the flue. r he other end of the flue is reduced in diameter', as shown at 4l, by compression rolls or suitable devices, to rthe extent of about three-sixteenths of an inch, and the exterior' of this section is tl'rreaded. llorliing on the threaded section e is an annular sleeve or nut 5, the external surface of which is conical and corresponds in its taper and in its diameter to the conical exterior surface of tne upset or thickened end section Vrlith these dimensions the sleeve nut 5 will have a maximum thickness of wall section of one-eighth of inch from the bottom of its threads to its external conical surface.

The object of making the conical exterior surface of the sleeve 5 and upset end portion 3 of the same taper and diameter is to male the llue reversible; that is, capable of being inserted. into the boiler through either of the Ihre sheets thereof, and of being secured with either end applied to either flue sheet. The llue sheets l are formed with slightly tapered flue seats G, and between these seats and the conical surfaces of the tapered parts 3 and 5, as the case may be, are interposed soft bushings 7 that are preferably held in place by being` svv'aged into the said seats, as set forth and claimed in my Patent 829,508, issued to me of date August 28, 1906. In the device disclosed and claimed in my said companion application, the end portions of the llue were not contracted; and hence it was necessary to malle the upset conical end of the ihre of much greate diameter than in the present construction, in order to obtain the proper thickness of metal in the wall of said conical section. This was also true with respect to the conical sleeve nut. These relatively large conical sections made necessary the use of correspondingly large seats in the flue sheet, which unnecessarily weaken said flue sheets, and, furthermore, in applying the llue to boilers already constructed required a large amount of unnecessary reaming, in order to properly enlarge the flue seats in the already constructed l'lue sheets.

By the improved arrangement above described, both of the above noted objectionable features are removed, that is, flue seats of a minimum diameter are made possible,

and at the same time the proper thickness of wall in the conical end of the flue and in the conical sleeve nut is provided.

ln practice, l have found that the slight reduction in the internal diameter of the flues at the ends thereof increases rather than decreases the efficiency of the boiler; Figs.

2, 3 and l illustrate diilerent steps of the process by which the upset tapered. end 3 is 7 0 produced. Fig. 2 shows the natural or commerci-al condition of the flue, by reference to which it will be seen that the end portion thereof is the same thickness and diameter as the body of the flue. The first step of the 7 5 process consists in reducing the end of the flue, both in external and internal diameter,

as shown in Fig. 3 and this may be done by compression rollers which act upon the flue under rotation while the flue is het, or it may be accomplished in any other suitable way and by any other suitable means. rlhe second step of the process consists in upsetting the reduced end of the flue, thereby increasing the external diameter thereof, especially toward the end of the lue as shown in Fig. il, without changing materially the internal diameter of the reduced portion. rl`he upsetting of the reduced end of the flue may be accomplished in any suitable way, as by pounding the same while hot against an anvil; and contraction of the internal diamei ter of the said reduced section may be prevented by placing therein, temporarily, ametal plug of the proper diameter.

The above described process of producing or upsetting the end of the 'flue is not herein claimed, but will be claimed in a separate application which will be Yfiled as a division of the present application.

l claim as my invention:

l. A boiler Vfue having one end reduced in internal diameter' and increased in external diameter, substantially as described.

2. A boiler flue having one end reduced in internal diameter and increased in external diameter, said increased external surface being conical and flaring toward the end of the flue, substantially as described.

3. A boiler flue having one end contracted and upset at 3, said section 3 having an internal diameter less than the internal diameter of the body of said rlue and having a conical exterior' surface that flares toward the end of the lue, substantially as described.

In testimony whereof l a'l'lix my signature in presence of two witnesses.

JOHN M. CROZIER.

Witnesses Marlin Henn, ll. D. lrteonn. 

